Avoiding Rush Hour with Utilizing Horizontal Directional Drilling

The city of Frisco, located just north of Dallas, Texas, has experienced a drastic population increase over the past 15 years. The rapid population growth coupled with recent drought conditions and limited overall water resource options posed an increased focus on water conservation efforts. This conservation effort, combined with an overall need for additional infrastructure to support a growing population, has resulted in two projects with major trenchless components to lessen the impact of construction on a fully developed commercial area along on of the city’s major thoroughfares. The first project was for a new reuse pipeline to convey treated wastewater from Stewart Creek West Wastewater Treatment Plant (SCWWWTP). The design included a total of 10,000 feet of 12-inch reuse pipeline and a booster pump station. While most of the pipeline was installed by open trenching within the roadway median, one section of the alignment employed horizontal directional drilling (HDD) methods to bore 2,500 feet of the reuse pipeline under a busy intersection that could not be open cut. Based on the reuse project’s success, the city decided to install approximately 4,000 feet of 18-inch and 10,000 feet of 20-inch sanitary sewer force main along a similar alignment to convey raw sewage to the SCWWWTP. The second project required installation of a 2,680-foot portion of the 20-inch force main via HDD. This paper will discuss the benefit that HDD provided and the challenges faced in drilling a compound curvilinear alignment with the encounter of hard rock formations.